Some of the OEMs listed by Microsoft as Windows RT partners had earlier publicly revealed designs or said they would deliver hardware based on the new operating system. Others not named by Microsoft, including Toshiba and Acer, had also announced plans previously.

In a post on the Building Windows 8 blog Monday, Mike Angiulo, the vice president of Microsoft's ecosystem and planning team, declined to go into specifics of each OEM's planned products -- he left that for the vendors to do themselves closer to the October launch of Windows 8 and Windows RT -- but he did spell out some specification ranges for the new hardware.

The upcoming devices will include both tablets and laptops, and run the gamut of form factors. "Some of our Windows RT PCs come with full keyboard and touchpad solutions, whether removable/dockable or a traditional clamshell," Angiulo said.

According to Angiulo, some of the new Windows RT devices will be up to 11 percent thinner than Apple's iPad, and weigh 20 percent less than the Cupertino, Calif., company's iconic tablet.

Others will be considerably larger, with the top of the scale 84 percent heavier than the iPad -- 2.64 pounds was the mass leader -- and at sixth-tenths of an inch, 66 percent thicker.

Screens sizes will range from 10.1 to 11.6 inches, said Angiulo, which would give them all more real estate -- but not necessarily pixels, since he did not offer information on the resolution of those displays -- than the iPad's 9.7-inch screen.

Angiulo, keeping to Microsoft's secrecy line, said nothing about a price range for the Windows RT devices from the four OEMs. The company has declined to discuss prices of its Surface RT, as well as the slightly-larger tablet based on Windows 8 Pro.

"Very rarely have any of these [Building Windows 8] posts been unplanned," Moorhead argued. "This is their way of encapsulating the devices that partners have discussed, and to show that there is still interest in Windows RT, even after [it announced] Surface."

More specifically, Moorhead saw the blog as a reaction to the belief by many that few partners would support Windows RT, especially after Acer executives hammered Microsoft for horning in on the hardware game.

It also follows the announcement from Lenovo, the world's second-largest OEM, of a thin, lightweight tablet powered by an Intel processor that runs the more inclusive Windows 8.

"I think this was driven by the Lenovo tablet," said Moorhead, referring to the ThinkPad Tablet 2 introduced last week. "I have a tablet that's less than 10mm thick and claims around 9 hours of battery life, but it's running an Intel processor and Windows 8. So what's the value of Windows RT again, when I can have my cake and eat it too?" Moorhead asked.

Moorhead also said his between-the-lines reading of Angiulo's blog showed Microsoft wants to convince customers that they'll get a more consistent experience with Windows RT hardware than with Windows 8.

"There will be a limited range of display sizes for Windows RT," Moorhead observed, talking about the 10.1- to 11.6-inch screens Microsoft said it and its OEMs would use.

Angiulo reinforced that by contrasting the limitations of Windows RT with the kitchen sink approach for Windows 8's form factors.

"You can expect to see everything from ultra-thin sleek designs with stunning high-resolution displays, to beautifully designed all-in-one PCs with large immersive displays complete with touch, to high-power towers rocking multiple graphics cards and high-performance storage arrays," Angiulo said of the new OS that runs both tile-style apps and traditional desktop software.